Method and apparatus for manufacturing optical fiber preform

Abstract

A method and an apparatus for manufacturing an optical fiber preform. The method manufactures the optical fiber preform by depositing soot created through a chemical reaction on an inside wall of a reaction tube. The created soot is charged with a first predetermined charge to adhere soot, which is not deposited on the inside wall of the tube, to an electrified body charged with a second predetermined charge opposite to the first predetermined charge. The electrified body is adapted for movement to transport the unused soot to an exterior of the reaction tube. The electrified body is energized with a charge identical to the first predetermined charge of soot, thereby exhausting soot adhering to the electrified body to an exterior of the reaction tube.

1 . A method for removing unused soot when manufacturing an optical fiber preform by soot deposition created through a chemical reaction on an inside wall of a reaction tube, the method comprising the steps of: 
 (a) charging unused soot that is not deposited on the inside wall of the tube with a first predetermined charge;    (b) adhering the unused soot to an electrified body charged with a second predetermined charge, in which said second predetermined charge is opposite in polarity to the first predetermined charge;    (c) moving the electrified body having soot adhered thereto to an exterior of the quartz reaction tube; and    (d) removing soot adhering to the electrified body that has been moved to an exterior of the reaction tube.    
   
   
       2 . The method according to  claim 1 , wherein step (d) further includes: 
 (i) subsequently charging the electrified body with a charge identical to the first predetermined charge of soot to discharge the soot adhered to the electrified body.    
   
   
       3 . The method according to  claim 2 , wherein: 
 the first predetermined charge in step (a) comprises a positive charge, and    the second predetermined charge in step (b) comprises a negative charge.    
   
   
       4 . The method according to  claim 1 , wherein the electrified body in step (c) is moved next to a cleaner body having a predetermined charge that is equal in polarity and greater in magnitude to the second predetermined charge sufficient to attract the soot from the electrified body to the cleaner body.  
   
   
       5 . The method according to  claim 1 , wherein the reaction tube is comprised of quartz.  
   
   
       6 . The method according to  claim 5 , further comprising heating the quartz tube during at least a portion of formation of the fiber preform.  
   
   
       7 . A method for removing unused soot when manufacturing an optical fiber preform by soot deposition created through a chemical reaction on an inside wall of a reaction tube, the method comprising the steps of: 
 (a) creating soot through a chemical reaction in a tube, wherein a first portion of the soot created is deposited on an inside wall of the reaction tube;    (b) charging the soot in the reaction tube with a first predetermined charge; and    (c) removing a remaining portion of the soot by adhering the remaining portion to an electrified body that is adapted for movement inside and exterior to the reaction tube.    
   
   
       8 . The method according to  claim 7 , wherein the removing in step (c) comprises 
 (i) first charging the electrified body with a second predetermined charge, in which said second predetermined charge is opposite in polarity to the first predetermined charge;    (ii) moving the electrified body to an area exterior to the reaction tube; and    (iii) subsequently charging the electrified body with a charge identical to the first predetermined charge of soot to discharge the soot adhered to the electrified body.    
   
   
       9 . The method according to  claim 7 , wherein the reaction tube is comprised of quartz.  
   
   
       10 . The method according to  claim 7 , wherein the soot is created in step (a) by chemical vapor deposition and deposited on the tube by thermophoresis, wherein a plurality of predetermined raw materials are inserted into the reaction tube and heated.  
   
   
       11 . An apparatus for manufacturing an optical fiber preform by depositing soot created from raw material gas injected into a reaction tube through a chemical reaction, the apparatus comprising: 
 a soot exhausting device for removing excessive soot formed in the quartz reaction tube, the soot exhausting device including,    a first electrified body adapted for reciprocal movement in left and right directions along a major axis of the reaction tube so as to charge excessive soot formed in the reaction tube with a first predetermined charge;    a second electrified body absorbing soot by being charged with a second predetermined charge, which is opposite in polarity to the first predetermined charge, when the second electrified body inserted into the quartz reaction tube, and exhausting soot to an exterior of the quartz reaction tube by being charged with a charge identical to the first predetermined charge of soot after retreating to the exterior of the quartz reaction tube; and    a controller for controlling a movement and a conductive state of the second electrified body.    
   
   
       12 . The apparatus as claimed in  claim 11  further comprising: 
 a table rotatably supporting both side ends of the reaction tube at each sidewall thereof, and having a guiding groove at a bottom surface thereof;    a burner heating an outer surface of the reaction tube;    a sliding member provided on an upper surface thereof with the burner and the first electrified body in such a manner that the burner and the first electrified body are spaced from each other, and adapted for a reciprocating movement in left and right directions along the guide groove in parallel to a major axis of the reaction tube; and    a pair of chucks passing each through a respective sidewall of the table so as to rotatably fix the reaction tube to the table.    
   
   
       13 . The apparatus as claimed in  claim 11 , wherein the reaction tube is comprised of quartz.  
   
   
       14 . The apparatus as claimed in  claim 12 , wherein the sliding member having a threading in a center portion, and a feed screw adapted to engage with the threading in said sliding member, and a motor adapted for rotating the feed screw, so that said sliding member being adapted for movement in a longitudinal direction along the guiding groove.  
   
   
       15 . The apparatus as claimed in  claim 11 , wherein the first electrified body and the second electrified body comprise electromagnets.  
   
   
       16 . The apparatus as claimed in  claim 11 , wherein the first electrified body comprises a charge corona.  
   
   
       17 . The apparatus as claimed in  claim 12 , wherein a first chuck of said pair of chucks includes a passage for movement of raw material gas into the reaction tube.  
   
   
       18 . The apparatus as claimed in  claim 17 , wherein a second chuck of said pair of chucks includes a passage for movement of the second electrified body therethrough.